U.S. patent number 4,514,976 [Application Number 06/422,118] was granted by the patent office on 1985-05-07 for integrated auxiliary power and environmental control unit.
This patent grant is currently assigned to Rockwell International Corporation. Invention is credited to William J. Christoff.
United States Patent |
4,514,976 |
Christoff |
May 7, 1985 |
Integrated auxiliary power and environmental control unit
Abstract
An integrated auxiliary power unit and environmental control
unit for an airplane 2, said integrated unit 2 comprising a prime
mover 4, a variable geometry compressor 22 operable selectably by
bleed air from the propulsion engine of said airplane or
connectable via an overrunning clutch 18 to said prime mover, a
controlled emission turbine 24 which is shaft-coupled to said
compressor 22 and cooperating with said compressor to form an
environmental control unit, and means for diverting a portion of
the output of said compressor for use as an auxiliary power
unit.
Inventors: |
Christoff; William J. (Thousand
Oaks, CA) |
Assignee: |
Rockwell International
Corporation (El Segundo, CA)
|
Family
ID: |
23673467 |
Appl.
No.: |
06/422,118 |
Filed: |
September 23, 1982 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
155369 |
Jun 2, 1980 |
|
Dec 30, 1982 |
|
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Current U.S.
Class: |
60/785;
60/39.183; 60/39.15 |
Current CPC
Class: |
F02C
6/06 (20130101); B64D 41/00 (20130101); F02C
7/26 (20130101); B64D 13/06 (20130101); Y02T
50/671 (20130101); Y02T 50/40 (20130101); Y02T
50/60 (20130101); Y02T 50/50 (20130101); Y02T
50/56 (20130101); Y02T 50/44 (20130101); F05D
2220/50 (20130101); B64D 2013/0611 (20130101) |
Current International
Class: |
B64D
13/00 (20060101); B64D 13/06 (20060101); B64D
41/00 (20060101); F02C 6/00 (20060101); F02C
6/06 (20060101); F02C 7/26 (20060101); F02C
006/08 () |
Field of
Search: |
;60/39.07,39.142,39.15,39.183,39.33 ;98/1.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Casaregola; Louis J.
Attorney, Agent or Firm: Hamann; H. Fredrick Field; Harry
B.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of copending application
Ser. No. 155,369, filed June 2, 1980, and abandoned on Dec. 30,
1982.
Claims
What is claimed and desired to be secured by Letters Patent of the
United States:
1. An integrated environmental control and auxiliary power unit for
a vehicle having a propulsion engine, said unit comprising:
a prime mover;
a variable geometry compressor including a diffuser having a
plurality of controllable variable exit vanes;
means for positioning said variable exit vanes to control the
output flow of said compressor;
an overrunning clutch operable to couple said prime mover to drive
said compressor;
means for supplying bleed air from said propulsion engine to drive
said compressor when said prime mover is not running;
a controlled emission turbine coupled to said compressor by a
common drive shaft;
means for blocking a selectable portion of the flow supplied to
said turbine to match the flow from said compressor to maintain
near constant pressure to said turbine over a wide flow operating
range; and
means for independently utilizing the output flow from said
compressor and from said turbine.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to turbomachinery and is particularly
directed to integrated auxiliary power and environmental control
units for aircraft and the like.
2. Description of the Prior Art
In large aircraft, it has been the custom, heretofore, to provide
an auxiliary power unit, comprising a prime mover driving a
compressor, which served to provide compressed air for powering the
airplane air cycle environmental control unit, or for powering the
airplane engine air starters. In passenger planes, it has been
customary to also provide an environmental control unit for
cooling, heating and pressurization of the passenger compartment.
This unit has comprised a turbine which may be driven either by
bleed air from the airplane's propulsion engines or by compressed
air provided by a separate prime mover (auxiliary power unit). The
prime mover mechanically drives a compressor for providing
additional air flow to the environmental control unit turbine, to
provide both the proper aircraft ventilation rate and provide an
energy source for the environmental control cycle. Air flow from
the environmental control unit turbine is also provided to the
aircraft cabin at the desired temperature and pressure. It has been
conventional, heretofore, to drive the compressor of the
environmental control unit at maximum output to provide a maximum
flow rate for the limiting heating or cooling condition and adjust
the output flow temperature by flow mixing through a temperature
control valve. In large passenger planes, it has been customary to
provide a plurality of independent environmental control units.
It will be apparent that, where a plurality of independent
environmental control units are provided, it is also necessary to
provide a corresponding plurality of sensor and control systems. It
should also be noted that, with the systems of the prior art, it
has been necessary to operate each of these environmental control
unit compressors at maximum output at all times, regardless of the
actual demand, in order to be able to accommodate a range of
potential demands. Obviously, this is not energy efficient.
BRIEF SUMMARY OF THE INVENTION
These disadvantages of the prior art are overcome with the present
invention. Means are provided for accomplishing the functions of an
auxiliary power units plus a plurality of environmental control
units, of the prior art, with substantially improved energy
efficiency, reduced complexity, lower operating and maintenance
costs and lighter, less expensive equipment.
The advantages of the present invention are preferably attained by
providing an auxiliary power unit comprising a prime mover and a
variable geometry compressor. These can be driven by bleed air from
the plane's propulsion engines or can be connected through an
overrunning clutch to be driven by said prime mover. The compressor
is shaft-coupled to a controlled emission turbine which cooperates
with said compressor to form an environmental control unit. When
the compressor is directly driven by the prime mover, it can serve
the needs of both the auxiliary power unit and the environmental
control unit. Alternatively, when the plane is in flight, the
compressor can be decoupled from the power unit by means of the
overrunning clutch, and can be driven by bleed air from the plane's
propulsion engines to serve the environmental control unit.
It will be seen that the single compressor of the present invention
replaces two compressors in prior art equipment. This provides
substantial reductions in weight and size, which can be translated
into greater payback or reduced requirements for a given payload.
In addition, the variable geometry compressor has variable exit
vanes which can be adjusted to regulate flow to the turbine to
substantially constant pressure, and thereby maintain near peak
operating efficiencies. The turbine emission can be controlled by
partitioning the flow supply to achieve flow matching with the
compressor, to minimize pressure throttling to the turbine and,
hence, to maintain near constant pressure over a wide flow
operating range. This also permits a portion of the compressor
discharge air to be diverted from the turbine for other purposes,
such as driving an engine starter motor. In addition, this
arrangement enables the environmental control unit to operate at
constant speed, near peak design efficiency, throughout most of the
operating range. Consequently, the system of the present invention
is highly energy efficient.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a method and
apparatus for accomplishing the functions of an auxiliary power
unit and an environmental control unit in apparatus which is
compact, light-weight, energy efficient and economical to install
and maintain.
Another object of the present invention is to provide a combined
auxiliary power unit and environmental control unit which operates
at constant speed, near peak design efficiency, over a wide
operating range.
A specific object of the present invention is to provide an
integrated auxiliary power unit and environmental control unit for
an airplane, said integrated unit comprising a prime mover, a
variable diffuser compressor operable selectably by bleed air from
the propulsion engine of said airplane or connectable via an
overrunning clutch to said prime mover, a controlled emission
turbine which is shaft coupled to said compressor and cooperating
with said compressor to form an environmental control unit, and
means for diverting a portion of the output of said compressor for
use as an auxiliary power unit.
These and other objects and features of the present invention will
be apparent from the following detailed description, taken with
reference to the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic representation of an integrated auxiliary
power and environmental control unit embodying the present
invention.
FIG. 2 depicts the partitioning means at the turbine input of the
present invention.
FIG. 3 is a block diagram of the control circuitry for the
compressor output and turbine input flow regulators of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In that form of the present invention chosen for purposes of
illustration, the Figures show an integrated auxiliary power unit
and environmental control unit, indicated generally at 2, having a
prime mover 4 which drives a gearbox 6 and through gearbox 6,
drives a variety of equipment, such as generator 8, cooling fan 10,
fuel pump 12, lubrication pump 14 and overrunning clutches 16 and
18. Clutch 16 is engageable for drive starter 20 to rotate prime
mover 4 through gearbox 6, for starting prime mover 4. Clutch 18 is
engageable to drive a variable geometry compressor 22 and a
controlled emission turbine 24 which are mounted on a common drive
shaft 26.
The variable geometry compressor 22 includes a diffuser having
variable exit vanes which are adjustable to control the flow area
and pressure of air passing into or out of the compressor 22. This
permits operation of the compressor 22 at nearly constant pressure
and near peak efficiency with low energy utilization, with prime
mover 4 providing minimal drive power or, if prime mover 4 is
inactive, compressor 22 is driven by a minimal amount of engine
bleed air, as seen at 28 in the figures. If desired, a variable set
of compressor inlet guide vanes can also be added to further reduce
the energy utilization of the environmental control unit. Such
compressors are components of the Lycoming T55-L11 aircraft engine,
manfactured by AVCO Lycoming Corporation, Stratford, Conn., and as
components of engines developed by the National Aeronautics and
Space Administration. The controlled emission turbine 24 uses
controllable inlet ducting as depicted in FIG. 2 to partition the
amount of air flow input to the turbine, while maintaining
substantially constant pressure so as to assure operation of the
turbine 24 at near peak efficiency. This permits adjustment of the
emission from turbine 24 to match the flow from compressor 22 which
minimizes pressure throttling to the turbine and permits
maintenance of near constant pressure over a wide flow operating
range. The compressor 22 and the flow partitioning turbine 24 are
precalibrated such that the diffuser vane setting and the turbine
inlet partition 31 setting each correspond to the same percentage
of full (100%) flow. For example, the turbine inlet partition of
FIG. 2 may be set to allow air flow through each of turbine inlet
25, 27 and 29 or 100% flow, it may be set to block inlet 25 to
provide 75% flow or it may be set to block both inlets 25 and 27,
providing 50% flow. In the preferred embodiment, inlet 29 is always
open, assuring that the turbine has at least 50% of the possible
inlet flow. The diffuser vane settings will be set to provide the
appropriate output to match any of the three allowable turbine
inlet settings.
The diffuser vanes and turbine inlet partition may be controlled by
a number of conventional means such as electrical motors, hydraulic
or pneumatic means or the like. In the preferred embodiment of the
invention, the control means comprises electric motors coupled to a
controller 30 which is programmed to respond to flow control logic
as explained in detail hereinbelow. Table A is provided as an aid
to understanding the logic.
TABLE A ______________________________________ Temperature
Conditions dT/dt > dT/dt < 2.degree./10 Sec .dwnarw. .fwdarw.
2.degree./10 Sec dT/dt > 2.degree./min dT/dt < 2.degree./min
______________________________________ Ts-Tc > 2.degree. 100%
100% 100% Ts-Tc < 2.degree. 50% 75% Maintain Position Setting
.BHorizBrace. Signal to Compressor and Turbine
______________________________________
As depicted in FIG. 3, controller 30 comprises flow control section
32, monitor section 34 and override section 36. Flow control
section 32 receives input data from cabin temperature setting
control (Ts) 38, cabin temperature sensor (Tc), and cabin
temperature rate of change circuit (dT/dt) 42. Referring now to
TABLE A, it is seen that if Ts-Tc is greater than 2.degree. F.,
flow control section 32 will signal compressor 22 to provide and
flow partitioned turbine 24 to accept, 100% flow. This corresponds
to all of the turbine 24 inlets 25,27 and 29 of FIG. 2 being open.
If Ts-Tc<2.degree. F. and dT/dt>2.degree. F./10 sec., flow
control section 32 will signal the compressor 22 to provide and
turbine 24 to accept 50% flow. If Ts-Tc<2.degree. and dT/dt is
less than 2.degree. F./10 seconds but greater than 2.degree.
F./minute, flow control section 32 will signal the compressor 22 to
provide and the turbine 24 to accept, 75% flow. Finally, if
Ts-Tc<2.degree. F. and dT/dt<2.degree. F./min the flow
control section 32 will maintain the compressor vane and partition
setting previously set.
Monitor section 34 counts the number of flow change signals to
compressor 22 and turbine 24. If controller 30 cycles between the
same two flow positions more than once in a ten-minute period,
monitor section 34 will set the flow rate to the higher of the two
positions and hold the setting for 10 minutes before again allowing
flow control secton 32 to determine if the flow should be changed.
Additionally, override section 36 constantly compares the turbine
inlet flow to the preprogrammed minimum cabin ventilation
requirement. If flow control 32 requests a flow rate below the
minimum requirement, it will be overridden by override section
34.
The integrated system of the present invention combines the energy
saving features of an energy-efficient, recirculating,
environmental control unit and an auxiliary power unit into a
single integrated unit, which can be controlled to expend less
energy than a separate environmental control unit and a separate
auxiliary power unit, throughout the aircraft mission. Obviously,
combining the environmental control unit and auxiliary power unit
permits elimination of one compressor, with attendant savings in
weight, space, installation and operating costs. Furthermore, shaft
coupling of the compressor and turbine is about 98% efficient,
while conventional air coupling is only about 80% efficient.
Numerous variations and modifications may be made without departing
from the present invention. Accordingly, it should be clearly
understood that the form of the present invention described above
and shown in the accompanying drawings is illustrative only and is
not intended to limit the scope of the present invention.
* * * * *